1. Technical Field
This invention relates in general to variable focal length lenses and in particular to a variable focal length, liquid crystal lens assembly.
2. Background Art
In the prior art, focus adjustment in an image sensing device such as video camera is made by moving lenses with a motor. The motor, complicated mechanisms required to move the lenses, and their power requirements make it difficult to implement these devices in small, lightweight applications.
Focus adjusting devices which use liquid crystal as a lens material, such as those disclosed in U.S. Pat. No. 4,037,929, can change focal length without deforming the lens. The lens uses small voltages to alter the refractive index of the liquid crystal and, thus, change the focal length of the lens. However, it is difficult to change the refractive index of the lens by more than about 20%, and the focal distance cannot be reduced sufficiently. Thus, an liquid crystal lens with greater focal length range is needed.